The gram-negative pathogen Pseudomonas aeruginosa uses N-acylated-L-homoserine lactones (AHLs) in quorum sensing to modulate transcriptional activators, including LasR, and regulate the expression of virulence factors. The same AHLs suppress the host immune system. CAY10654 is a synthetic analog of natural AHLs that suppresses host immunity without inducing LasR. It inhibits the proliferation of mouse peripheral blood leukocytes by concanavalin A (EC50 = 9.3 μM) without concurrent cytotoxicity. LasR is not induced by 100 μM CAY10654, although LasR is potently induced by natural AHL (5 μM) in positive control experiments.
